/* $OpenBSD: tls13_server.c,v 1.96 2022/02/03 16:33:12 jsing Exp $ */ /* * Copyright (c) 2019, 2020 Joel Sing * Copyright (c) 2020 Bob Beck * * Permission to use, copy, modify, and distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice appear in all copies. * * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ #include #include "ssl_locl.h" #include "ssl_sigalgs.h" #include "ssl_tlsext.h" #include "tls13_handshake.h" #include "tls13_internal.h" int tls13_server_init(struct tls13_ctx *ctx) { SSL *s = ctx->ssl; if (!ssl_supported_tls_version_range(s, &ctx->hs->our_min_tls_version, &ctx->hs->our_max_tls_version)) { SSLerror(s, SSL_R_NO_PROTOCOLS_AVAILABLE); return 0; } s->version = ctx->hs->our_max_tls_version; tls13_record_layer_set_retry_after_phh(ctx->rl, (s->internal->mode & SSL_MODE_AUTO_RETRY) != 0); if (!ssl_get_new_session(s, 0)) /* XXX */ return 0; tls13_record_layer_set_legacy_version(ctx->rl, TLS1_VERSION); if (!tls1_transcript_init(s)) return 0; arc4random_buf(s->s3->server_random, SSL3_RANDOM_SIZE); return 1; } int tls13_server_accept(struct tls13_ctx *ctx) { if (ctx->mode != TLS13_HS_SERVER) return TLS13_IO_FAILURE; return tls13_handshake_perform(ctx); } static int tls13_client_hello_is_legacy(CBS *cbs) { CBS extensions_block, extensions, extension_data, versions; uint16_t version, max_version = 0; uint16_t type; CBS_dup(cbs, &extensions_block); if (!CBS_get_u16_length_prefixed(&extensions_block, &extensions)) return 1; while (CBS_len(&extensions) > 0) { if (!CBS_get_u16(&extensions, &type)) return 1; if (!CBS_get_u16_length_prefixed(&extensions, &extension_data)) return 1; if (type != TLSEXT_TYPE_supported_versions) continue; if (!CBS_get_u8_length_prefixed(&extension_data, &versions)) return 1; while (CBS_len(&versions) > 0) { if (!CBS_get_u16(&versions, &version)) return 1; if (version >= max_version) max_version = version; } if (CBS_len(&extension_data) != 0) return 1; } return (max_version < TLS1_3_VERSION); } int tls13_client_hello_required_extensions(struct tls13_ctx *ctx) { SSL *s = ctx->ssl; /* * RFC 8446, section 9.2. If the ClientHello has supported_versions * containing TLSv1.3, presence or absence of some extensions requires * presence or absence of others. */ /* * If we got no pre_shared_key, then signature_algorithms and * supported_groups must both be present. */ if (!tlsext_extension_seen(s, TLSEXT_TYPE_pre_shared_key)) { if (!tlsext_extension_seen(s, TLSEXT_TYPE_signature_algorithms)) return 0; if (!tlsext_extension_seen(s, TLSEXT_TYPE_supported_groups)) return 0; } /* * supported_groups and key_share must either both be present or * both be absent. */ if (tlsext_extension_seen(s, TLSEXT_TYPE_supported_groups) != tlsext_extension_seen(s, TLSEXT_TYPE_key_share)) return 0; /* * XXX - Require server_name from client? If so, we SHOULD enforce * this here - RFC 8446, 9.2. */ return 1; } static const uint8_t tls13_compression_null_only[] = { 0 }; static int tls13_client_hello_process(struct tls13_ctx *ctx, CBS *cbs) { CBS cipher_suites, client_random, compression_methods, session_id; STACK_OF(SSL_CIPHER) *ciphers = NULL; const SSL_CIPHER *cipher; uint16_t legacy_version; int alert_desc; SSL *s = ctx->ssl; int ret = 0; if (!CBS_get_u16(cbs, &legacy_version)) goto err; if (!CBS_get_bytes(cbs, &client_random, SSL3_RANDOM_SIZE)) goto err; if (!CBS_get_u8_length_prefixed(cbs, &session_id)) goto err; if (!CBS_get_u16_length_prefixed(cbs, &cipher_suites)) goto err; if (!CBS_get_u8_length_prefixed(cbs, &compression_methods)) goto err; if (tls13_client_hello_is_legacy(cbs) || s->version < TLS1_3_VERSION) { if (!CBS_skip(cbs, CBS_len(cbs))) goto err; return tls13_use_legacy_server(ctx); } ctx->hs->negotiated_tls_version = TLS1_3_VERSION; ctx->hs->peer_legacy_version = legacy_version; /* Ensure we send subsequent alerts with the correct record version. */ tls13_record_layer_set_legacy_version(ctx->rl, TLS1_2_VERSION); /* Add decoded values to the current ClientHello hash */ if (!tls13_clienthello_hash_init(ctx)) { ctx->alert = TLS13_ALERT_INTERNAL_ERROR; goto err; } if (!tls13_clienthello_hash_update_bytes(ctx, (void *)&legacy_version, sizeof(legacy_version))) { ctx->alert = TLS13_ALERT_INTERNAL_ERROR; goto err; } if (!tls13_clienthello_hash_update(ctx, &client_random)) { ctx->alert = TLS13_ALERT_INTERNAL_ERROR; goto err; } if (!tls13_clienthello_hash_update(ctx, &session_id)) { ctx->alert = TLS13_ALERT_INTERNAL_ERROR; goto err; } if (!tls13_clienthello_hash_update(ctx, &cipher_suites)) { ctx->alert = TLS13_ALERT_INTERNAL_ERROR; goto err; } if (!tls13_clienthello_hash_update(ctx, &compression_methods)) { ctx->alert = TLS13_ALERT_INTERNAL_ERROR; goto err; } if (!tlsext_server_parse(s, SSL_TLSEXT_MSG_CH, cbs, &alert_desc)) { ctx->alert = alert_desc; goto err; } /* Finalize first ClientHello hash, or validate against it */ if (!ctx->hs->tls13.hrr) { if (!tls13_clienthello_hash_finalize(ctx)) { ctx->alert = TLS13_ALERT_INTERNAL_ERROR; goto err; } } else { if (!tls13_clienthello_hash_validate(ctx)) { ctx->alert = TLS13_ALERT_ILLEGAL_PARAMETER; goto err; } tls13_clienthello_hash_clear(&ctx->hs->tls13); } if (!tls13_client_hello_required_extensions(ctx)) { ctx->alert = TLS13_ALERT_MISSING_EXTENSION; goto err; } /* * If we got this far we have a supported versions extension that offers * TLS 1.3 or later. This requires the legacy version be set to 0x0303. */ if (legacy_version != TLS1_2_VERSION) { ctx->alert = TLS13_ALERT_PROTOCOL_VERSION; goto err; } /* Store legacy session identifier so we can echo it. */ if (CBS_len(&session_id) > sizeof(ctx->hs->tls13.legacy_session_id)) { ctx->alert = TLS13_ALERT_ILLEGAL_PARAMETER; goto err; } if (!CBS_write_bytes(&session_id, ctx->hs->tls13.legacy_session_id, sizeof(ctx->hs->tls13.legacy_session_id), &ctx->hs->tls13.legacy_session_id_len)) { ctx->alert = TLS13_ALERT_INTERNAL_ERROR; goto err; } /* Parse cipher suites list and select preferred cipher. */ if ((ciphers = ssl_bytes_to_cipher_list(s, &cipher_suites)) == NULL) { ctx->alert = TLS13_ALERT_ILLEGAL_PARAMETER; goto err; } cipher = ssl3_choose_cipher(s, ciphers, SSL_get_ciphers(s)); if (cipher == NULL) { tls13_set_errorx(ctx, TLS13_ERR_NO_SHARED_CIPHER, 0, "no shared cipher found", NULL); ctx->alert = TLS13_ALERT_HANDSHAKE_FAILURE; goto err; } ctx->hs->cipher = cipher; sk_SSL_CIPHER_free(s->session->ciphers); s->session->ciphers = ciphers; ciphers = NULL; /* Ensure only the NULL compression method is advertised. */ if (!CBS_mem_equal(&compression_methods, tls13_compression_null_only, sizeof(tls13_compression_null_only))) { ctx->alert = TLS13_ALERT_ILLEGAL_PARAMETER; goto err; } ret = 1; err: sk_SSL_CIPHER_free(ciphers); return ret; } int tls13_client_hello_recv(struct tls13_ctx *ctx, CBS *cbs) { SSL *s = ctx->ssl; if (!tls13_client_hello_process(ctx, cbs)) goto err; /* See if we switched back to the legacy client method. */ if (s->method->version < TLS1_3_VERSION) return 1; /* * If a matching key share was provided, we do not need to send a * HelloRetryRequest. */ /* * XXX - ideally NEGOTIATED would only be added after record protection * has been enabled. This would probably mean using either an * INITIAL | WITHOUT_HRR state, or another intermediate state. */ if (ctx->hs->key_share != NULL) ctx->handshake_stage.hs_type |= NEGOTIATED | WITHOUT_HRR; /* XXX - check this is the correct point */ tls13_record_layer_allow_ccs(ctx->rl, 1); return 1; err: return 0; } static int tls13_server_hello_build(struct tls13_ctx *ctx, CBB *cbb, int hrr) { uint16_t tlsext_msg_type = SSL_TLSEXT_MSG_SH; const uint8_t *server_random; CBB session_id; SSL *s = ctx->ssl; uint16_t cipher; cipher = SSL_CIPHER_get_value(ctx->hs->cipher); server_random = s->s3->server_random; if (hrr) { server_random = tls13_hello_retry_request_hash; tlsext_msg_type = SSL_TLSEXT_MSG_HRR; } if (!CBB_add_u16(cbb, TLS1_2_VERSION)) goto err; if (!CBB_add_bytes(cbb, server_random, SSL3_RANDOM_SIZE)) goto err; if (!CBB_add_u8_length_prefixed(cbb, &session_id)) goto err; if (!CBB_add_bytes(&session_id, ctx->hs->tls13.legacy_session_id, ctx->hs->tls13.legacy_session_id_len)) goto err; if (!CBB_add_u16(cbb, cipher)) goto err; if (!CBB_add_u8(cbb, 0)) goto err; if (!tlsext_server_build(s, tlsext_msg_type, cbb)) goto err; if (!CBB_flush(cbb)) goto err; return 1; err: return 0; } static int tls13_server_engage_record_protection(struct tls13_ctx *ctx) { struct tls13_secrets *secrets; struct tls13_secret context; unsigned char buf[EVP_MAX_MD_SIZE]; uint8_t *shared_key = NULL; size_t shared_key_len = 0; size_t hash_len; SSL *s = ctx->ssl; int ret = 0; if (!tls_key_share_derive(ctx->hs->key_share, &shared_key, &shared_key_len)) goto err; s->session->cipher = ctx->hs->cipher; if ((ctx->aead = tls13_cipher_aead(ctx->hs->cipher)) == NULL) goto err; if ((ctx->hash = tls13_cipher_hash(ctx->hs->cipher)) == NULL) goto err; if ((secrets = tls13_secrets_create(ctx->hash, 0)) == NULL) goto err; ctx->hs->tls13.secrets = secrets; /* XXX - pass in hash. */ if (!tls1_transcript_hash_init(s)) goto err; tls1_transcript_free(s); if (!tls1_transcript_hash_value(s, buf, sizeof(buf), &hash_len)) goto err; context.data = buf; context.len = hash_len; /* Early secrets. */ if (!tls13_derive_early_secrets(secrets, secrets->zeros.data, secrets->zeros.len, &context)) goto err; /* Handshake secrets. */ if (!tls13_derive_handshake_secrets(ctx->hs->tls13.secrets, shared_key, shared_key_len, &context)) goto err; tls13_record_layer_set_aead(ctx->rl, ctx->aead); tls13_record_layer_set_hash(ctx->rl, ctx->hash); if (!tls13_record_layer_set_read_traffic_key(ctx->rl, &secrets->client_handshake_traffic)) goto err; if (!tls13_record_layer_set_write_traffic_key(ctx->rl, &secrets->server_handshake_traffic)) goto err; ctx->handshake_stage.hs_type |= NEGOTIATED; if (!(SSL_get_verify_mode(s) & SSL_VERIFY_PEER)) ctx->handshake_stage.hs_type |= WITHOUT_CR; ret = 1; err: freezero(shared_key, shared_key_len); return ret; } int tls13_server_hello_retry_request_send(struct tls13_ctx *ctx, CBB *cbb) { int nid; ctx->hs->tls13.hrr = 1; if (!tls13_synthetic_handshake_message(ctx)) return 0; if (ctx->hs->key_share != NULL) return 0; if ((nid = tls1_get_shared_curve(ctx->ssl)) == NID_undef) return 0; if ((ctx->hs->tls13.server_group = tls1_ec_nid2curve_id(nid)) == 0) return 0; if (!tls13_server_hello_build(ctx, cbb, 1)) return 0; return 1; } int tls13_server_hello_retry_request_sent(struct tls13_ctx *ctx) { /* * If the client has requested middlebox compatibility mode, * we MUST send a dummy CCS following our first handshake message. * See RFC 8446 Appendix D.4. */ if (ctx->hs->tls13.legacy_session_id_len > 0) ctx->send_dummy_ccs_after = 1; return 1; } int tls13_client_hello_retry_recv(struct tls13_ctx *ctx, CBS *cbs) { SSL *s = ctx->ssl; if (!tls13_client_hello_process(ctx, cbs)) return 0; /* XXX - need further checks. */ if (s->method->version < TLS1_3_VERSION) return 0; ctx->hs->tls13.hrr = 0; return 1; } static int tls13_servername_process(struct tls13_ctx *ctx) { uint8_t alert = TLS13_ALERT_INTERNAL_ERROR; if (!tls13_legacy_servername_process(ctx, &alert)) { ctx->alert = alert; return 0; } return 1; } int tls13_server_hello_send(struct tls13_ctx *ctx, CBB *cbb) { if (ctx->hs->key_share == NULL) return 0; if (!tls_key_share_generate(ctx->hs->key_share)) return 0; if (!tls13_servername_process(ctx)) return 0; ctx->hs->tls13.server_group = 0; if (!tls13_server_hello_build(ctx, cbb, 0)) return 0; return 1; } int tls13_server_hello_sent(struct tls13_ctx *ctx) { /* * If the client has requested middlebox compatibility mode, * we MUST send a dummy CCS following our first handshake message. * See RFC 8446 Appendix D.4. */ if ((ctx->handshake_stage.hs_type & WITHOUT_HRR) && ctx->hs->tls13.legacy_session_id_len > 0) ctx->send_dummy_ccs_after = 1; return tls13_server_engage_record_protection(ctx); } int tls13_server_encrypted_extensions_send(struct tls13_ctx *ctx, CBB *cbb) { if (!tlsext_server_build(ctx->ssl, SSL_TLSEXT_MSG_EE, cbb)) goto err; return 1; err: return 0; } int tls13_server_certificate_request_send(struct tls13_ctx *ctx, CBB *cbb) { CBB certificate_request_context; if (!CBB_add_u8_length_prefixed(cbb, &certificate_request_context)) goto err; if (!tlsext_server_build(ctx->ssl, SSL_TLSEXT_MSG_CR, cbb)) goto err; if (!CBB_flush(cbb)) goto err; return 1; err: return 0; } static int tls13_server_check_certificate(struct tls13_ctx *ctx, SSL_CERT_PKEY *cpk, int *ok, const struct ssl_sigalg **out_sigalg) { const struct ssl_sigalg *sigalg; SSL *s = ctx->ssl; *ok = 0; *out_sigalg = NULL; if (cpk->x509 == NULL || cpk->privatekey == NULL) goto done; /* * The digitalSignature bit MUST be set if the Key Usage extension is * present as per RFC 8446 section 4.4.2.2. */ if (!(X509_get_key_usage(cpk->x509) & X509v3_KU_DIGITAL_SIGNATURE)) goto done; if ((sigalg = ssl_sigalg_select(s, cpk->privatekey)) == NULL) goto done; *ok = 1; *out_sigalg = sigalg; done: return 1; } static int tls13_server_select_certificate(struct tls13_ctx *ctx, SSL_CERT_PKEY **out_cpk, const struct ssl_sigalg **out_sigalg) { SSL *s = ctx->ssl; const struct ssl_sigalg *sigalg; SSL_CERT_PKEY *cpk; int cert_ok; *out_cpk = NULL; *out_sigalg = NULL; cpk = &s->cert->pkeys[SSL_PKEY_ECC]; if (!tls13_server_check_certificate(ctx, cpk, &cert_ok, &sigalg)) return 0; if (cert_ok) goto done; cpk = &s->cert->pkeys[SSL_PKEY_RSA]; if (!tls13_server_check_certificate(ctx, cpk, &cert_ok, &sigalg)) return 0; if (cert_ok) goto done; cpk = NULL; sigalg = NULL; done: *out_cpk = cpk; *out_sigalg = sigalg; return 1; } int tls13_server_certificate_send(struct tls13_ctx *ctx, CBB *cbb) { SSL *s = ctx->ssl; CBB cert_request_context, cert_list; const struct ssl_sigalg *sigalg; X509_STORE_CTX *xsc = NULL; STACK_OF(X509) *chain; SSL_CERT_PKEY *cpk; X509 *cert; int i, ret = 0; if (!tls13_server_select_certificate(ctx, &cpk, &sigalg)) goto err; if (cpk == NULL) { /* A server must always provide a certificate. */ ctx->alert = TLS13_ALERT_HANDSHAKE_FAILURE; tls13_set_errorx(ctx, TLS13_ERR_NO_CERTIFICATE, 0, "no server certificate", NULL); goto err; } ctx->hs->tls13.cpk = cpk; ctx->hs->our_sigalg = sigalg; if ((chain = cpk->chain) == NULL) chain = s->ctx->extra_certs; if (chain == NULL && !(s->internal->mode & SSL_MODE_NO_AUTO_CHAIN)) { if ((xsc = X509_STORE_CTX_new()) == NULL) goto err; if (!X509_STORE_CTX_init(xsc, s->ctx->cert_store, cpk->x509, NULL)) goto err; X509_VERIFY_PARAM_set_flags(X509_STORE_CTX_get0_param(xsc), X509_V_FLAG_LEGACY_VERIFY); X509_verify_cert(xsc); ERR_clear_error(); chain = X509_STORE_CTX_get0_chain(xsc); } if (!CBB_add_u8_length_prefixed(cbb, &cert_request_context)) goto err; if (!CBB_add_u24_length_prefixed(cbb, &cert_list)) goto err; if (!tls13_cert_add(ctx, &cert_list, cpk->x509, tlsext_server_build)) goto err; for (i = 0; i < sk_X509_num(chain); i++) { cert = sk_X509_value(chain, i); /* * In the case of auto chain, the leaf certificate will be at * the top of the chain - skip over it as we've already added * it earlier. */ if (i == 0 && cert == cpk->x509) continue; /* * XXX we don't send extensions with chain certs to avoid sending * a leaf ocsp staple with the chain certs. This needs to get * fixed. */ if (!tls13_cert_add(ctx, &cert_list, cert, NULL)) goto err; } if (!CBB_flush(cbb)) goto err; ret = 1; err: X509_STORE_CTX_free(xsc); return ret; } int tls13_server_certificate_verify_send(struct tls13_ctx *ctx, CBB *cbb) { const struct ssl_sigalg *sigalg; uint8_t *sig = NULL, *sig_content = NULL; size_t sig_len, sig_content_len; EVP_MD_CTX *mdctx = NULL; EVP_PKEY_CTX *pctx; EVP_PKEY *pkey; const SSL_CERT_PKEY *cpk; CBB sig_cbb; int ret = 0; memset(&sig_cbb, 0, sizeof(sig_cbb)); if ((cpk = ctx->hs->tls13.cpk) == NULL) goto err; if ((sigalg = ctx->hs->our_sigalg) == NULL) goto err; pkey = cpk->privatekey; if (!CBB_init(&sig_cbb, 0)) goto err; if (!CBB_add_bytes(&sig_cbb, tls13_cert_verify_pad, sizeof(tls13_cert_verify_pad))) goto err; if (!CBB_add_bytes(&sig_cbb, tls13_cert_server_verify_context, strlen(tls13_cert_server_verify_context))) goto err; if (!CBB_add_u8(&sig_cbb, 0)) goto err; if (!CBB_add_bytes(&sig_cbb, ctx->hs->tls13.transcript_hash, ctx->hs->tls13.transcript_hash_len)) goto err; if (!CBB_finish(&sig_cbb, &sig_content, &sig_content_len)) goto err; if ((mdctx = EVP_MD_CTX_new()) == NULL) goto err; if (!EVP_DigestSignInit(mdctx, &pctx, sigalg->md(), NULL, pkey)) goto err; if (sigalg->flags & SIGALG_FLAG_RSA_PSS) { if (!EVP_PKEY_CTX_set_rsa_padding(pctx, RSA_PKCS1_PSS_PADDING)) goto err; if (!EVP_PKEY_CTX_set_rsa_pss_saltlen(pctx, -1)) goto err; } if (!EVP_DigestSignUpdate(mdctx, sig_content, sig_content_len)) goto err; if (EVP_DigestSignFinal(mdctx, NULL, &sig_len) <= 0) goto err; if ((sig = calloc(1, sig_len)) == NULL) goto err; if (EVP_DigestSignFinal(mdctx, sig, &sig_len) <= 0) goto err; if (!CBB_add_u16(cbb, sigalg->value)) goto err; if (!CBB_add_u16_length_prefixed(cbb, &sig_cbb)) goto err; if (!CBB_add_bytes(&sig_cbb, sig, sig_len)) goto err; if (!CBB_flush(cbb)) goto err; ret = 1; err: if (!ret && ctx->alert == 0) ctx->alert = TLS13_ALERT_INTERNAL_ERROR; CBB_cleanup(&sig_cbb); EVP_MD_CTX_free(mdctx); free(sig_content); free(sig); return ret; } int tls13_server_finished_send(struct tls13_ctx *ctx, CBB *cbb) { struct tls13_secrets *secrets = ctx->hs->tls13.secrets; struct tls13_secret context = { .data = "", .len = 0 }; struct tls13_secret finished_key = { .data = NULL, .len = 0 } ; uint8_t transcript_hash[EVP_MAX_MD_SIZE]; size_t transcript_hash_len; uint8_t *verify_data; size_t verify_data_len; unsigned int hlen; HMAC_CTX *hmac_ctx = NULL; CBS cbs; int ret = 0; if (!tls13_secret_init(&finished_key, EVP_MD_size(ctx->hash))) goto err; if (!tls13_hkdf_expand_label(&finished_key, ctx->hash, &secrets->server_handshake_traffic, "finished", &context)) goto err; if (!tls1_transcript_hash_value(ctx->ssl, transcript_hash, sizeof(transcript_hash), &transcript_hash_len)) goto err; if ((hmac_ctx = HMAC_CTX_new()) == NULL) goto err; if (!HMAC_Init_ex(hmac_ctx, finished_key.data, finished_key.len, ctx->hash, NULL)) goto err; if (!HMAC_Update(hmac_ctx, transcript_hash, transcript_hash_len)) goto err; verify_data_len = HMAC_size(hmac_ctx); if (!CBB_add_space(cbb, &verify_data, verify_data_len)) goto err; if (!HMAC_Final(hmac_ctx, verify_data, &hlen)) goto err; if (hlen != verify_data_len) goto err; CBS_init(&cbs, verify_data, verify_data_len); if (!CBS_write_bytes(&cbs, ctx->hs->finished, sizeof(ctx->hs->finished), &ctx->hs->finished_len)) goto err; ret = 1; err: tls13_secret_cleanup(&finished_key); HMAC_CTX_free(hmac_ctx); return ret; } int tls13_server_finished_sent(struct tls13_ctx *ctx) { struct tls13_secrets *secrets = ctx->hs->tls13.secrets; struct tls13_secret context = { .data = "", .len = 0 }; /* * Derive application traffic keys. */ context.data = ctx->hs->tls13.transcript_hash; context.len = ctx->hs->tls13.transcript_hash_len; if (!tls13_derive_application_secrets(secrets, &context)) return 0; /* * Any records following the server finished message must be encrypted * using the server application traffic keys. */ return tls13_record_layer_set_write_traffic_key(ctx->rl, &secrets->server_application_traffic); } int tls13_client_certificate_recv(struct tls13_ctx *ctx, CBS *cbs) { CBS cert_request_context, cert_list, cert_data, cert_exts; struct stack_st_X509 *certs = NULL; SSL *s = ctx->ssl; X509 *cert = NULL; EVP_PKEY *pkey; const uint8_t *p; int cert_type; int ret = 0; if (!CBS_get_u8_length_prefixed(cbs, &cert_request_context)) goto err; if (CBS_len(&cert_request_context) != 0) goto err; if (!CBS_get_u24_length_prefixed(cbs, &cert_list)) goto err; if (CBS_len(&cert_list) == 0) { if (!(s->verify_mode & SSL_VERIFY_FAIL_IF_NO_PEER_CERT)) return 1; ctx->alert = TLS13_ALERT_CERTIFICATE_REQUIRED; tls13_set_errorx(ctx, TLS13_ERR_NO_PEER_CERTIFICATE, 0, "peer did not provide a certificate", NULL); goto err; } if ((certs = sk_X509_new_null()) == NULL) goto err; while (CBS_len(&cert_list) > 0) { if (!CBS_get_u24_length_prefixed(&cert_list, &cert_data)) goto err; if (!CBS_get_u16_length_prefixed(&cert_list, &cert_exts)) goto err; p = CBS_data(&cert_data); if ((cert = d2i_X509(NULL, &p, CBS_len(&cert_data))) == NULL) goto err; if (p != CBS_data(&cert_data) + CBS_len(&cert_data)) goto err; if (!sk_X509_push(certs, cert)) goto err; cert = NULL; } /* * At this stage we still have no proof of possession. As such, it would * be preferable to keep the chain and verify once we have successfully * processed the CertificateVerify message. */ if (ssl_verify_cert_chain(s, certs) <= 0) { ctx->alert = ssl_verify_alarm_type(s->verify_result); tls13_set_errorx(ctx, TLS13_ERR_VERIFY_FAILED, 0, "failed to verify peer certificate", NULL); goto err; } ERR_clear_error(); /* * Achtung! Due to API inconsistency, a client includes the peer's leaf * certificate in the stored certificate chain, while a server does not. */ cert = sk_X509_shift(certs); if ((pkey = X509_get0_pubkey(cert)) == NULL) goto err; if (EVP_PKEY_missing_parameters(pkey)) goto err; if ((cert_type = ssl_cert_type(pkey)) < 0) goto err; X509_up_ref(cert); X509_free(s->session->peer_cert); s->session->peer_cert = cert; s->session->peer_cert_type = cert_type; s->session->verify_result = s->verify_result; sk_X509_pop_free(s->session->cert_chain, X509_free); s->session->cert_chain = certs; certs = NULL; ctx->handshake_stage.hs_type |= WITH_CCV; ret = 1; err: sk_X509_pop_free(certs, X509_free); X509_free(cert); return ret; } int tls13_client_certificate_verify_recv(struct tls13_ctx *ctx, CBS *cbs) { const struct ssl_sigalg *sigalg; uint16_t signature_scheme; uint8_t *sig_content = NULL; size_t sig_content_len; EVP_MD_CTX *mdctx = NULL; EVP_PKEY_CTX *pctx; EVP_PKEY *pkey; X509 *cert; CBS signature; CBB cbb; int ret = 0; memset(&cbb, 0, sizeof(cbb)); if (!CBS_get_u16(cbs, &signature_scheme)) goto err; if (!CBS_get_u16_length_prefixed(cbs, &signature)) goto err; if (!CBB_init(&cbb, 0)) goto err; if (!CBB_add_bytes(&cbb, tls13_cert_verify_pad, sizeof(tls13_cert_verify_pad))) goto err; if (!CBB_add_bytes(&cbb, tls13_cert_client_verify_context, strlen(tls13_cert_client_verify_context))) goto err; if (!CBB_add_u8(&cbb, 0)) goto err; if (!CBB_add_bytes(&cbb, ctx->hs->tls13.transcript_hash, ctx->hs->tls13.transcript_hash_len)) goto err; if (!CBB_finish(&cbb, &sig_content, &sig_content_len)) goto err; if ((cert = ctx->ssl->session->peer_cert) == NULL) goto err; if ((pkey = X509_get0_pubkey(cert)) == NULL) goto err; if ((sigalg = ssl_sigalg_for_peer(ctx->ssl, pkey, signature_scheme)) == NULL) goto err; ctx->hs->peer_sigalg = sigalg; if (CBS_len(&signature) > EVP_PKEY_size(pkey)) goto err; if ((mdctx = EVP_MD_CTX_new()) == NULL) goto err; if (!EVP_DigestVerifyInit(mdctx, &pctx, sigalg->md(), NULL, pkey)) goto err; if (sigalg->flags & SIGALG_FLAG_RSA_PSS) { if (!EVP_PKEY_CTX_set_rsa_padding(pctx, RSA_PKCS1_PSS_PADDING)) goto err; if (!EVP_PKEY_CTX_set_rsa_pss_saltlen(pctx, -1)) goto err; } if (!EVP_DigestVerifyUpdate(mdctx, sig_content, sig_content_len)) { ctx->alert = TLS13_ALERT_DECRYPT_ERROR; goto err; } if (EVP_DigestVerifyFinal(mdctx, CBS_data(&signature), CBS_len(&signature)) <= 0) { ctx->alert = TLS13_ALERT_DECRYPT_ERROR; goto err; } ret = 1; err: if (!ret && ctx->alert == 0) ctx->alert = TLS13_ALERT_DECODE_ERROR; CBB_cleanup(&cbb); EVP_MD_CTX_free(mdctx); free(sig_content); return ret; } int tls13_client_end_of_early_data_recv(struct tls13_ctx *ctx, CBS *cbs) { return 0; } int tls13_client_finished_recv(struct tls13_ctx *ctx, CBS *cbs) { struct tls13_secrets *secrets = ctx->hs->tls13.secrets; struct tls13_secret context = { .data = "", .len = 0 }; struct tls13_secret finished_key; uint8_t *verify_data = NULL; size_t verify_data_len; uint8_t key[EVP_MAX_MD_SIZE]; HMAC_CTX *hmac_ctx = NULL; unsigned int hlen; int ret = 0; /* * Verify client finished. */ finished_key.data = key; finished_key.len = EVP_MD_size(ctx->hash); if (!tls13_hkdf_expand_label(&finished_key, ctx->hash, &secrets->client_handshake_traffic, "finished", &context)) goto err; if ((hmac_ctx = HMAC_CTX_new()) == NULL) goto err; if (!HMAC_Init_ex(hmac_ctx, finished_key.data, finished_key.len, ctx->hash, NULL)) goto err; if (!HMAC_Update(hmac_ctx, ctx->hs->tls13.transcript_hash, ctx->hs->tls13.transcript_hash_len)) goto err; verify_data_len = HMAC_size(hmac_ctx); if ((verify_data = calloc(1, verify_data_len)) == NULL) goto err; if (!HMAC_Final(hmac_ctx, verify_data, &hlen)) goto err; if (hlen != verify_data_len) goto err; if (!CBS_mem_equal(cbs, verify_data, verify_data_len)) { ctx->alert = TLS13_ALERT_DECRYPT_ERROR; goto err; } if (!CBS_write_bytes(cbs, ctx->hs->peer_finished, sizeof(ctx->hs->peer_finished), &ctx->hs->peer_finished_len)) goto err; if (!CBS_skip(cbs, verify_data_len)) goto err; /* * Any records following the client finished message must be encrypted * using the client application traffic keys. */ if (!tls13_record_layer_set_read_traffic_key(ctx->rl, &secrets->client_application_traffic)) goto err; tls13_record_layer_allow_ccs(ctx->rl, 0); ret = 1; err: HMAC_CTX_free(hmac_ctx); free(verify_data); return ret; }